In a scroll compressor having a suction stroke in which refrigerant gas is introduced from a suction port into a suction chamber and further into the largest closed space of a compression chamber in the compressor, means has been proposed for ensuring communication the largest closed space with the suction port side until just before formation of the largest closed space in a compression chamber insofar as possible with a view to decreasing fluid resistance of the fluid to the compression chamber during suction.
As such a scroll compressor, one disclosed in Japanese Patent Laid-Open No. H 11(1999)-336678 (Patent Literature 1) is known for example.
In this known scroll compressor, upright spiral laps are provided on base plates of a fixed scroll and a movable scroll, as a fixed scroll lap and a movable scroll lap respectively, in such a manner that the movable scroll performs a swivel motion relative to the fixed scroll. The fixed scroll lap and the movable scroll lap are engaged with each other to form a suction chamber and compression chambers. A suction port communicating with the suction chamber is provide in the fixed scroll and further a communication groove extending from the suction port to the suction chamber is provide in the fixed scroll. The communication groove can communicate with the suction chamber until just before formation of the largest closed space in the compression chamber.
In the above publication it is shown that with the communication groove provide din the fixed scroll, the sectional area of the fluid flow path in the suction space increases and it is possible to decrease an agitation loss induced within the suction space by the movable scroll lap. It is also shown therein that by ensuring communication between the suction chamber and the communication groove until just before formation of the largest closed space in the compression chamber, it is possible to decrease a loss caused by a compressing operation involving leakage which is generated in the suction stroke.
[Patent Literature 1]
Japanese Patent Laid-Open No. H 11(1999)-336678 (FIG. 11)
In Patent Literature 1, however, there is found no disclosure regarding a flow path loss attributable to the shape of the communication groove itself formed in the fixed scroll. For example, it has turned out that the loss by the communication groove would increase extremely, if the communicating groove had a flat surface on the bottom and a depth which was able to make its communication between the suction port and the communication groove with their sufficient openings. With such a communication groove, refrigerant gas flowing from the suction port into the communication groove strikes against a vertical surface at the front end of the communication groove, resulting in that the flow of the refrigerant gas is greatly disturbed and the flow path loss caused by the communication groove becomes extremely large. In view of this point, if the communication groove is made shallow, there arises the problem that the flow path loss diminishing effect resulting from a decrease of the flow path resistance on the suction side by the communication groove is reduced by half.
In Patent Literature 1, for largest closed spaces in compression chambers formed on an inner line side and an outer line side of a winding end portion of the movable scroll lap, independent communication grooves are formed in the fixed scroll and the movable scroll, respectively, resulting in the structure becoming complicated and the cost becoming high.